Here's an idea I've been looking to try out in a magical girl RP; A team pet capable of fighting
The basic idea is this; a semi intelligent animal from a magical world where humans don't exist has found a viewing portal to look into our world. After spending years watching our world, he has grown obsessed with humans and now wants to become one. When the villain begins their attack, the viewing portal becomes disrupted and briefly turns into a wormhole, sucking him in and transporting him to the human world. When he gets there, he finds himself with a new human form with a strange belt and ring. Finally able to live his dream, he sets out to train himself to be fully human...only to discover a catch; he can't remain in human form for very long. After enough time has passed, he'll revert back to his animal form
Power wise, he would use his ring and belt to transform himself into
this. Which would sever as his base form. His Regalia form would be a little more complex; see, he doesn't have his own Regalia form. However, he can borrow someone else's. By touching his right hand to a Jewelmancers' left, a ring appears on that hand called a Crystal Beast Ring. When he uses it on his belt, he gets a mantel on his right shoulder with the head of whatever animal is on the ring. The power of each mantel varies
I had a similar, fruit themed idea for a Sailor Moon RP that never got off the ground